Dengue virus infection. Animation of a dendritic cell (cream) that is infected with dengue virus, activating a T lymphocyte (purple). The virus is replicating inside the dendritic cell and releasing new virus particles (dark green). Dendritic cells and T lymphocytes are components of the body's immune system. Dendritic cells are antigen-presenting cells (APCs), that is, they present pathogens or foreign molecules (antigens) to other cells of the immune system, including T lymphocytes, to be eliminated. Dengue virus, transmitted by the bite of Aedes sp. mosquitoes, causes the tropical disease dengue fever in humans. Symptoms can range from a mild fever and joint pain to spontaneous bleeding of the skin and circulatory failure, which are often fatal.